Regressive Changes in the Superficial Layer of Human Articular Cartilage

Abstract

A study was made to determine whether changes of a regressive nature can be detected in the superficial layer of adult human articular cartilage before the onset of osteo-arthritic fibrillation and to examine the morphology of superficial fibrillation. Articular cartilage from babies and children was used as a standard against which to compare the degree of change in adult samples from persons ranging in age from 28 - 82 years. The cartilage samples were from the central aspect of the upper end of humerus and near the edge of a femoral condyle. Many of the sections from adults include nonfibrillated areas in which the superficial layer shows depletion of matrix ground substance, nuclear degeneration and the formation of clear or empty lacunae which may indicate the site of effete cells. These features are confined to a narrow band of cartilage lying immediately beneath the articular surface in their least developed form; they extend deeply into the superficial layer in their advanced form. Non-fibrillated areas showing some degree of regressive change are showing some degree of regressive change are common both in adult samples from the upper end of the humerus and from the femoral condyle, but regressive change is usually more advanced in the femoral samples, and a much higher proportion of these samples also include areas of actual osteo-arthritic fibrillation. Non-fibrillated areas immediately adjacent to fibrillated sites show an advanced stage of regression. Osteo-arthritic fibrillation may develop as an extension of regressive change. Early fibrillation is characterized by fraying of the articular surface to form long narrow strands and shorter broad-based tufts. Small pits are seen in the cartilage surface probably formed by the rupture of erosion of enlarged lacunae.